南京工业区夏冬季节二次有机气溶胶浓度估算及来源解析

Estimating the Secondary Organic Aerosol Concentration and Source Apportionment During the Summer and Winter in the Nanjing Industrial District

采用2015年6月15日~7月15日及2015年12月16日~2016年1月15日期间GC5000在线气相色谱仪得到的挥发性有机物(volatile organic compounds,VOCs)数据、DRI-2001A热/光碳分析仪对膜采样分析得到的EC(elemental carbon)、OC(organic carbon)数据,使用气溶胶生成系数法(fractional aerosol coefficient,FAC)、EC示踪法及正矩阵因子分析(positive matrix factorization,PMF)对南京工业区二次有机气溶胶(secondary organic aerosol,SOA)浓度进行估算及来源解析.研究发现南京工业区SOA污染主要来源于芳香烃类物质,其对夏、冬季节SOA贡献率分别为80.39%、94.63%,主要贡献者为苯、甲苯、乙苯、二甲苯(benzene、toluene、ethylbenzene、xylene,BTEX);对南京工业区SOA浓度进行估算,得到夏季SOA浓度值为5.84~20.88μg·m^(-3),平均浓度为12.15μg·m^(-3),冬季为2.17~17.73μg·m^(-3),平均浓度为6.91μg·m^(-3),冬季SOA浓度平均水平明显低于夏季.SOA浓度值随风速及降水量的增大而减小;使用PMF受体模型对VOCs进行源解析分析得到夏季SOA污染主要来源于涂料使用、石油加工及石油化工源,SOA贡献值分别为0.65、0.21、0.18μg·m^(-3).冬季SOA污染主要来自于涂料使用,SOA贡献值为0.94μg·m^(-3).

Volatile organic compounds（VOCs） were determined by GC5000,an automatic on-line Gas Chromatography-Flame Ionization Detector. Elemental carbon（EC） and organic carbon（OC） were determined by the thermal/optical method using DRI-2001 A during the periods of June 15^th-July 15^th2015 and December 16^th2015-January 15^th2016. The concentration of secondary organic aerosol（SOA） was estimated by fractional aerosol coefficients（FAC） and EC tracer method. The source apportionment relied on the positive matrix factorization model（PMF）. There were several conclusions： First,aromatic hydrocarbon was the main substance causing the SOA pollution in the Nanjing Industrial district,the contributions of aromatic hydrocarbon to SOA during summer and winter were 80. 39% and 94. 63%,respectively. The main contributers were benzene,toluene,ethylbenzene,m,p-xylene and oxylene（BTEX）. In the summer,SOA concentration ranged from 5. 84-20. 88 μg·m^-3with an average of 12. 15 μg·m^-3and in the winter ranged from 2. 17-17. 73 μg·m^-3in which the average concentration was 6. 91 μg·m^-3. Secondly,SOA concentration decreased when wind and precipitation increased. By using the PMF model,a total of 7sources of SOA were determined in summer and6 were determined in winter. There were 3 main sources in summer,including painting,petroleum processing and petrochemical industry,and the contributions to SOA were 0. 65 μg·m^-3,0. 21 μg·m^-3,0. 18 μg·m^-3,respectively. In winter,the most important SOA pollution was from painting,in which the contribution was 0. 94 μg·m^-3.